I recently did this myself. The options I had were:
Try to adapt some fog lights into the stock 4x2 valance which never did look right
Buy a 4x4 XLT or Edge valance and adapt it to the 4x2 bumper by cutting off the "ears"
Or...do like I did
Buy a 4x4 XLT or Edge bumper and lower valance which have the fog light openings and the correct bumper that requires no modification to either. I also picked up a radio bezel that has the spot for the factory fog-light switch, the switch, some harnesses I found at the salvage yard, and a relay and wired it up to operate the fogs. There is a good wiring diagram on this site somewhere that shows how to do this. Thats all done, but I haven't got around to actually ordering the fog light assemblies themselves. The whole setup looks completely factory installed and works great.
'03 XLT/FX4 L1 4x4 4.0 Arizona Beige Automatic (my weekend ride). '16 Ford Escape Titanium ecoboost (wifes ride) '16 Ford Escape S (my work ride)